ChipFind - документация

Электронный компонент: HA16117F

Скачать:  PDF   ZIP
HA16117F Series
CMOS Watchdog Timer
Description
The HA16117F Series of ICs make a micro-processor (MPU) system fail-safe by monitoring its power
supply to detect voltage drops, and monitoring a P-RUN (program running) pulse to detect system crashes.
Also referred to as watchdog timers, these devices are essential in systems that aim for high levels of crash
protection. Fabricated by a CMOS process, they consume little power and are ideally suited for battery-
operated systems.
These ICs are available in versions for industrial and communications equipment and automotive
applications, as well as for consumer products.
Functions
Power-on reset
Sends a
RES signal to the MPU for a fixed time at power-on
Watchdog timer (WDT)
Monitors a P-RUN signal from the MPU and sends the MPU a
RES signal if P-RUN departs from a
set frequency range
Auto-reset
Outputs
RES signals to the MPU at clocked intervals while P-RUN remains abnormal
Supply voltage supervision
Outputs a low
RES signal if the supply voltage (same as the MPU's V
CC
) falls below a low threshold
level (V
TL
). The threshold differs for different ICs in the series, allowing designers to choose an IC
matching system requirements (see ordering information)
Features
Low power consumption : Operating (ACC pin low) = 0.5 mW (Typ)
: Standby (ACC pin high) = 0.2 mW (Typ)
Watchdog timer on/off control by ACC input signal
Independent auto-reset high and low times (t
RH
and t
RL
)
Watchdog monitoring by frequency filtering (independent of duty cycle)
High-precision low voltage detection (
2%)
Space- and weight-saving 8-pin SOP package
HA16117F Series
2
Ordering Information
The HA16117F Series includes three ICs with different low threshold levels (V
TL
).
Type No.
Low Threshold Voltage (V
TL
)
HA16117FPA/FPAJ
4.4 V Typ
HA16117FPB/FPBJ
4.2 V Typ
HA16117FPC/FPCJ
4.0 V Typ
Pin Arrangement
8
7
6
5
V
CC
P-RUN
C
F
C
R
1
2
3
4
Tadj
ACC
GND
(Top view)
RES
Pin Description
Pin No.
Symbol
Function
1
V
CC
Power supply voltage input
2
P-RUN
Watchdog timer (WDT) input
3
C
F
Connected capacitor C
F
determines WDT filter characteristic
(normal frequency range)
4
C
R
Connected capacitor C
R
determines t
ON
for power-on reset and t
OFF
, t
RH
,
and t
RL
for auto-reset
5
RES
Reset signal output from WDT and voltage supervision circuits
6
GND
Ground
7
ACC
WDT on/off control input (on when ACC is low)
8
Tadj *
For adjusting t
RH
and t
OFF
(divide V
CC
to get the adjustment voltage)
Note:
The low-voltage threshold cannot be modified by changing the external resistors connected to the
Tadj pin.
HA16117F Series
3
Block Diagram
1
6
5
8
2
3
7
-
+
4
-
+
5 V
0.1
V
CC
GND
C
R
Tadj
R
1
510 k
R
2
750 k
P-RUN
0.01
C
F
ACC
PULSE from I/O port
W.D in
SW2
1.25 V
2.52 (117FA)
2.36 (117FB)
2.20 (117FC)
SW1
COMP.
COMP.
to Micro-
computer
RES
W.D in frequency (Hz)
duty 50%
W.D out
W.D out
duty (%)
duty n%
1/2 frequency
divider
GND
1
Operating: "Low"
Standby: "High"
n
f
L
/2
f
H
/2
Normal range
I
2
I
2
adjustment
I
1
Power-on and auto-reset circuit
(*I
1
< I
2
)
(SW1 and SW2 are active high)
Watchdog filter (f-duty converter)
Watchdog timer
Low voltage detector
ACC Voltage
Function
Low
Low voltage detection and WDT
Low voltage detection
Mode
Operating
Note: The power-on reset circuit operates in both operating and standby modes.
Standby
High
The HA16117F consists of a low voltage detector, power-on and auto-reset circuit, and watchdog timer.
Low Voltage Detector
Uses a reference voltage source (
1.25 V) and high-precision comparator to detect drops in the supply
voltage.
Power-On and Auto-Reset Circuit
Generates the
RES waveform, using a multivibrator consisting of a current source I
1
that charges the
external capacitor C
R
, a current source I
2
that discharges C
R
, and a comparator.
HA16117F Series
4
Watchdog Timer
Reshapes the P-RUN signal (programming-running pulse) from the MPU to obtain a 50% duty cycle, then
converts frequency to duty cycle in the watchdog filter (WD filter).
The watchdog filter is a bandpass filter. The duty cycle of the filter output is highest in the normal
frequency range of P-RUN.
The watchdog filter output controls I
2
in the multivibrator, the higher the duty cycle of the watchdog filter
output, the shorter the time during which I
2
discharges C
R
. If the duty cycle is high enough then C
R
is held
at a high potential, preventing the multivibrator from firing, and the
RES output remains high.
Absolute Maximum Ratings (Ta = 25
C)
Ratings
Item
Symbol
HA16117FPA/FPB/FPC
HA16117FPAJ/FPBJ/FPCJ
Unit
Power supply voltage
V
CC
0.3 to +14
0.3 to +14
V
P-RUN input voltage
V
P
V
CC
V
CC
V
ACC input voltage
V
ACC
14
14
V
RES output current
I
RES
10
10
mA
Permissible dissipation *
1
P
T
300
300
mW
Operating temperature range
Topr
30 to +85
40 to +85
C
Storage temperature
Tstg
55 to +125
55 to +125
C
Note:
1. This is the value when mounted on a glass epoxy substrate with 30% wiring density, up to an
ambient temperature of 83
C. Above that temperature, derate by 7.14 mW/
C.
40mm
Substrate
0.8 mm ceramic or
1.5 mm epoxy
400
300
200
100
0
-
30
-
20 0
20 40
Ambient operating temperature range Ta (
C)
60 80
85
C
-
7.14 mW/
C
(30% wiring density)
83
C
100
Permissible dissipation P
T
(mW)
HA16117F Series
5
Electrical Characteristics
(V
CC
= 5 V, Ta = 25
C, C
F
= 0.01
F, C
R
= 0.1
F, R
1
= 510 k
, R
2
= 750 k
)
Item
Symbol
Min
Typ
Max
Unit
Test Conditions
General
Operating supply current
I
CC1
--
100
--
A
V
ACC
= 0 V,
f
P-RUN
= 100 Hz
I
CC2
--
200
600
A
V
ACC
= 0 V,
f
P-RUN
= 20 kHz
Standby supply current
I
STBY
--
43
100
A
V
ACC
= 12 V
Low
voltage
detector
Low voltage
threshold
level
HA16117FPA/FPAJ
V
TL
4.3
4.4
4.5
V
When V
CC
drops
HA16117FPB/FPBJ
4.1
4.2
4.3
V
HA16117FPC/FPCJ
3.9
4.0
4.1
V
Hysteresis width
V
HYS
50
100
150
mV
ACC
Low input voltage
V
IL1
--
--
0.8
V
High input voltage
V
IH1
2.0
--
--
V
P-RUN
Low input voltage
V
IL2
--
--
0.8
V
input
High input voltage
V
IH2
2.0
--
--
V
WDT
Power-on reset time
t
ON
24
40
56
ms
Reset-clock off time
t
OFF
*
1
78
130
182
ms
Reset low time
t
RL
12
20
28
ms
Reset high time
t
RH
36
60
84
ms
P-RUN pin = 0 V
Low setup time
t
SL
1
--
--
ms
High setup time
t
SH
--
--
1
ms
RES
RES
low voltage
V
OL
--
--
0.4
V
I
OL
= 1 mA
output
RES
high voltage
V
OH
--
V
CC
--
V
Open
Reset function starting voltage
V
RES
--
0.8
1.4
V
Constant
range
Constant range of R
1
and R
2
K
0.55
0.6
0.8
--
K =R
2
/ (R
1
+ R
2
)
Operating supply voltage range
V
CCRNG
V
TL
--
6.0
V
Note:
1. Reset-clock off time t
OFF
is provided a shown in the under figure.
t
OFF
P-RUN
RES
f = 500 Hz, Duty = 50%